Transmission Operator
A transmission operator (TOP) is the entity responsible for the reliability of its local transmission system and operates or directs the operations of the transmission facilities. In the Electric Reliability Council of Texas (ERCOT) region, the ERCOT independent system operator is the sole registered TOP.
A TOP must meet the registration criteria listed below:
- An entity that operates an integrated transmission element associated with the bulk power system 100 kV and above, or lower voltage as defined by Texas Reliability Entity, Inc. (Texas RE) necessary to provide for the reliable operation of the interconnected transmission grid; or
- An entity that operates a transmission element below 100 kV associated with a facility that is included on a critical facilities list that is defined by Texas RE.
In addition to TOP, ERCOT ISO is registered as:
- Balancing Authority (BA)
- Interchange Authority (IA)
- Planning Authority (PA)
- Reliability Coordinator (RC)
- Resource Planner (RP)
- Transmission Service Provider (TSP)
For more information about registration criteria, refer to NERC’s Statement of Compliance Registry Criteria, found on the Compliance Registry 
page.
Exclusion: A TOP or a transmission owner will not be registered based on these criteria if responsibilities for compliance with approved NERC Reliability Standards or associated requirements including reporting have been transferred by written agreement to another entity that has registered for the appropriate function for the transferred responsibilities, such as a load-serving entity, generation-and-transmission cooperative, or joint action agency as described in Sections 501 and 507 of the NERC Rules of Procedure (found on the Compliance Registry page). See NERC Joint Registration Organizations for more on such agreements.